The invention relates to an optical emission device with a semiconductor emission chip and a cover. The aperture from which the light emerges is adapted for a desired radiation characteristic. Such optical emission devices are described, for Example, in U.S. Pat. No. 4,638,343 which issued on Jan. 20, 1987.
Special optical emission devices are required for the illumination of areas. Standard light emitting diodes (LEDs) and small incandescent light bulbs are generally designed so as to concentrate their radiation within a narrow cone in the axial direction (FIG. 1) and, therefore, the areas which can be illuminated homogeneously are narrowly limited zones. Furthermore, when using standard LEDs and light bulbs, large structural height and a high degree of packing density are required. The life of an LED is, moreover, greater by at least a factor of 100 over that of an incandescent light bulb.
As can be appreciated, there is a need for an optical emission device of the above-mentioned kind which lends itself to the function of backlighting areas, symbols and letters while being of comparatively low structural height and requiring a low packing density.